<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<script>
			var num1=parseInt(prompt("请输入第一个数"));
			var num2=prompt("运算符：+ - * /");
			var num3=parseInt(prompt("请输入第二个数"));
			switch(num2){
				case'+':
				alert(num1+num3);
				break;
				case'-':
				alert(num1-num3);
				break;
				case'*':
				alert(num1*num3);
				break;
				case'/':
				alert(num1/num3);
				break;
				default:
				alert("错误！");
				break;
			}
		</script>
	</body>
</html>
